1. Technical Field
The invention relates to a luminaire with at least one LED as luminous means and a method for operating the luminaire.
2. Prior Art
The light intensity of luminaires with LEDs is subject to fluctuations depending on the age and on the temperature of the LEDs. The ageing process has a particularly serious effect. A reduction of the light intensity to just 50% or less is possible. The light intensity changes only slowly and the alteration can hardly be perceived from the vicinity of operators.
A reduction of the light intensity is particularly critical in connection with applications for which specific luminous ranges are legally prescribed. A main area of application of the invention is navigation luminaires on ships. Luminaires of this type are also referred to as position lanterns and must have a luminous range of two nautical miles in the USA, for example. Other countries have in part different regulations.
When the light intensity of the LED decreases, the actual luminous range may fall below the legally prescribed value, so that the envisaged function is no longer fulfilled. Even without the presence of legal provisions, maintaining a specific light intensity for a luminaire is advantageous and desirable, for instance for illuminating traffic areas or properties or in connection with other types of signal and position luminaires.